Grey Magick Options

Greetings all of SM ~
I've come to ask a question on "Grey Magick", regarding the various outcomes that would lead to it either being white or black. As I've heard many examples as to how different spells can in turn become w/b, I've yet wondered in great detail if other variables of performing any spell can in turn overcome the initial goal and turn that spell into the opposite sort of magick.
I'm not entirely sure if this statement clarified my question well enough so I'll provide an example. Let's say perhaps you perform a spell to help a stranger come out of a coma, a coma that this stranger would never wake from, with no other background information on this stranger whatsoever, you decide being in a coma is just a terrible thing to endure in the long run. You run the divination process to put your mind at ease of what you want to accomplish and it turns out you have the green light. In this case, divination has told you no real negative influence has befallen your wish to return the stranger to his health. You go through with the spell, the man awakes and all is well. Two years later you understand this very stranger woke up one morning and decided to grab his own personal automatic rifle and go down to a super market and wreak havoc on 12 other lives before turning the gun on himself.
Now, I'm currently not a practicing magician. Perhaps, divination would enlighten you to events like this, though theres also so much the divination process can tell you about what you currently want done. Is an example like this accurate? Can it be? If so, to what incentive do the rest of us have to continue with magick if it will have unknowingly dramatic feedback.
I base my life on, everything having a purpose, every action causing a reaction that can potentially be bad or good. Even though I do a lot of good in my life through natural means, Im not going to truly know if that bit a good I just did, will take a turn for the worse. Is this how we're supposed to view magick?
Please, put my mind at ease. Thank you all in advance. (IMG:style_emoticons/default/egypt1.gif)

Let's say perhaps you perform a spell to help a stranger come out of a coma, a coma that this stranger would never wake from, with no other background information on this stranger whatsoever, you decide being in a coma is just a terrible thing to endure in the long run.

I have done this. A close online friend was a diabetic (unknown to me) and one day he disappeared. Another friend, who knew him also, reported that he had fallen into a diabetic coma and was staying at a hospital near me. This other friend came into town, and along with another person who knew the comatose man, we went to see him in the hospital. No one expected us there... he was unconscious on the bed in a sort of diaper, stuffed with medical equipment, and it was not a pleasant thing even though I had never met the guy in "real" life. I decided to use magic to save him,to prevent him from being claimed by the death his doctors pronounced likely soon to come.

I held my hands over him with a short spoken spell. I posted up a copy of the Tree of Life (the comatose man was into Qabalah) with our signatures on it in his room. He awoke very shortly after (we had already left) and began to recover, to the amazement of many doctors and all family members. Unfortunately he never healed completely, and over the course of several years he still had not fully recovered his full mental and physical capacity that had been damaged by the illness.

I try to be careful and to think ahead in all things, especially with magic. If this guy had gone berserk years after his healing, I would not begrudge having revived him.